Fiber lasers are a type of optical laser system that includes a clad fiber rather than a rod, a slab, or a disk. Fiber lasers reflect light through an optical cavity such that a stream of photons stimulates atoms in a fiber that store and release light energy at useful wavelengths. Fiber type, core size, numerical aperture, refractive index, and doping of the fiber contribute to the range and possibilities of light propagation using fiber laser systems. Fiber laser systems are used in many industrial, defense, and scientific applications for different purposes, including, telecommunications, spectroscopy, medicine, directed energy weapons, and cutting, marking, engraving, and etching various workpieces. Fiber laser systems have limitations, including failure modes tied to light reflected back to the fiber from the workpieces on which the fiber laser systems operate. Removal of back-reflected light can be problematic if measures are not taken to remove the unwanted light in such a way as to prevent concentrating the light into hot spots that can damage the optical laser system.